Recep Tayyip Erdoğan’s government has said it will do everything possible to bring the men back.
Photograph: Adem Altan/AFP/Getty Images

Greece has put in place the “greatest possible” measures to protect eight Turkish commandos accused of being coup plotters after Ankara warned it was a “national duty” to do everything within its power to bring them back.

A week after the men were freed from detention, Athens admitted they were under 24/7 guard at an undisclosed location, for fear of retaliation.

The admission came despite mounting tensions with Ankara, which last week suspended a refugee readmission deal with Athens, arguing the soldiers participated in the abortive coup against Recep Tayyip Erdoğan in July 2016.

Greece’s deputy defence minister, Fotis Kouvelis, told the Guardian: “We are enforcing the greatest possible measures to secure their safety in a place which for obvious reasons will remain unknown. We haven’t forgotten what happened in our region a few months ago.”

Kouvelis was referring to the enforced removal from Kosovo of six Turkish citizens also denounced as followers of the US-based cleric Fethullah Gülen, who Ankara has blamed for orchestrating the putsch.

Tensions over the eight men, who flew into Greece on a Black Hawk helicopter a day after the failed coup, have added to an increasingly fiery campaign ahead of snap presidential and parliamentary elections in Turkey on 24 June.

Friction with the west has escalated as the race appears to have tightened. At the weekend, Erdoğan accused Austria of fomenting a religious war between “cross” and “crescent” after it shut down overseas-funded mosques and raised the prospect of expelling Turkish Muslim clerics.

But it is Greece that has been the focus of growing animus in Ankara with bilateral relations approaching an all-time low. Addressing an election rally in the western city of Izmir on Sunday, the nationalist MHP leader Devlet Bahçeli, who in the run up to the election has joined forces with Erdoğan’s AK party, ramped up the rhetoric. “The Greeks,” he warned referring to their defeat in 1922 by Turkish troops in the city, “should not forget the days when their grandfathers drowned in the bottom of the sea. “

On Monday, Turkey’s EU minister Omer Celik said it was clear Athens was refusing to hand over the soldiers because it wanted to “extract secrets” from them.

Turkey has consistently argued the eight men were involved in the putsch against Erdoğan, which left 250 people dead and more than 2,000 injured.

The Greek supreme court has rejected any notion of sending the officers back, saying they would not get a fair trial in Turkey, where a purge of the military and civil establishment continues.

In April, the council of state, Greece’s highest administrative court, granted one of the eight commandos permanent asylum, despite objections by Alexis Tsipras’s leftist-led government. Similar judgments are expected to follow when verdicts are issued in the remaining cases.

The men, who deny involvement in the coup, were moved to the secret location when the 18-month period they were legally allowed to be held in detention expired last week.

Kouvelis said: “We have an independent justice system which applies EU laws, international laws. It’s not something we can ignore. We have to listen to it.”

Media reports on Sunday suggested the commandos were at risk of being abducted and assassinated. The newspaper Ta Nea reported that 80 police officers, including snipers, had been seconded to protect the Turks.

Kouvelis said air and sea violations by Turkish forces in the Aegean Sea had increased, with Turkey dispatching warships to its western shores facing Greece.

“A lot of ships have been transferred to the area and we are talking about fighter jets moving at crazy speeds, which raises the possibility of an accident,” he said.